MRIO for multiple counties and the state

I am trying to wrap my head around what I need to do to get at this. Let's say I have three contiguous counties (A, B, and C) that represents a region in a state. Within each of those three counties, a restaurant chain plans to open stores. County A gets 1 new store. County B gets 2 stores. County C gets 4 stores. Each store is about $500,000 to build. I want to measure the impact of the construction in the three counties, but include the spillovers from the other two counties as well. To me, the first part seems to require 6 MRIO models...AB, AC, BA, BC, CA, CB. The impact on the remainder of the state is the total of all construction from all new stores inside the region with the state as the state (less the three counties) as the second region in that last model...then add up appropriately to get the effects within each county...for example, there is the impact in A from building in A, but there is also the impact in A from building in B and C, captured by the lower part of the MRIO for BA and CA. Does this sound correct? thanks